Interactive Voice Response (IVR) systems automate phone-based workflows by prompting callers to provide a combination of voice and keypad commands, IVR can expedite many tasks, but callers may become impatient if forced to listen to and select from a large list of potential options. This issue is typically addressed with hierarchical voice prompts that narrow the options through a limited number of targeted questions. However, this solution is insufficient when presenting availability options (time slots) for fixture appointments. Applying the standard technique, a caller might first be required to choose a day and then choose a time only to discover that their preferred choice is unavailable. With no other mechanism providing guidance, the caller must blindly repeat the process until a suitable time (and day) is discovered.